Catalyst for preparing ethyl acetate through ethanol dehydrogenation as well as preparation method and application of catalyst

Abstract

The invention relates to a catalyst for preparing ethyl acetate through ethanol dehydrogenation, in particular to a CuO / ZnO / Al2O3 / ZrO2 / SiO2 catalyst. In addition, the invention also relates to a preparation method of the catalyst and application of the catalyst in preparation of ethyl acetate through ethanol dehydrogenation. The catalyst provided by the invention can efficiently convert ethanol into ethyl acetate, the conversion rate of ethanol can reach up to 71.05%, the selectivity of ethyl acetate can reach up to 94.55%, and the selectivity of methyl ethyl ketone can be as low as 1.32%. In addition, the catalyst provided by the invention has good stability.

Description

Technical Field

[0001] The present invention relates to a catalyst for the dehydrogenation of ethanol to ethyl acetate, in particular CuO / ZnO / Al 2 O 3 / ZrO 2 / SiO 2 catalyst. In addition, the present invention also relates to a preparation method of the catalyst and its use in the dehydrogenation of ethanol to ethyl acetate. Background Art

[0002] Ethyl acetate (abbreviated as EA) is flammable, has excellent solubility and fast drying property. It is an extractant for the production of products such as pharmaceuticals and organic acids, a medium or solvent for organic synthesis reactions, and also a chemical urgently needed in the textile industry, food industry, and perfume industry. In addition, in recent years, with the development of office automation, liquid nitrocellulose ink has also received extensive attention, and ethyl acetate can be used as a fast-drying solvent in nitrocellulose ink.

[0003] Currently, there are four methods for synthesizing ethyl acetate in the market: direct esterification of acetic acid / ethanol, synthesis esterification of acetic acid / ethylene, dehydrogenation disproportionation of ethanol, and acetaldehyde condensation method. Among them, the direct esterification of acetic acid / ethanol has problems such as high reaction temperature, low utilization rate of acetic acid, easy occurrence of side reactions, and strong acid corrosion. Compared with other methods, the synthesis esterification of acetic acid / ethylene has high-quality ethyl acetate products, easy control of purity, and is environmentally friendly, but the disadvantage is that the construction site is restricted and it must be built near an ethylene plant. The acetaldehyde condensation method is a mature industrial method at home and abroad, but there are limitations in raw material acetaldehyde, and there are also disadvantages such as difficult preparation of the catalyst, easy hydrolysis, and the need for cooling during the reaction process. The dehydrogenation disproportionation of ethanol selects ethanol, which is cheap and easily available, as the raw material, has a lower cost than the esterification method, mild reaction conditions, high product concentration, and no problems such as corrosion and environmental pollution. With the maturity of the coal-to-ethanol process, the dehydrogenation disproportionation of ethanol is a synthetic route with development prospects.

[0004] Cheng Yan et al. (Journal of Catalysis, Vol. 29, No. 10, 2008, pp. 1009-1014) selected different oxides (Al 2 O 3 、SiO 2 、TiO 2 、MgO) and H-ZSM-5 molecular sieve as carriers, and used urea as a precipitant to prepare a series of supported gold catalysts by the deposition-precipitation method. Among them, with Al 2 O 3When using [carrier], the selectivity of ethyl acetate is relatively high. When adding a small amount of basic additives, the formation of acetal can be inhibited and the conversion rate of ethanol and the selectivity of ethyl acetate can be increased. Under optimized conditions, the conversion rate of ethanol can reach 4.7%, and the selectivity of ethyl acetate can reach 93.5%. However, the conversion rate of ethanol of this catalyst is too low to meet the industrialization level.

[0005] Fu Zaihui et al. (Acta Catalytica Sinica, Vol. 4, No. 15, 1994, pp. 262 - 267) studied the one-step synthesis of ethyl acetate from ethanol over a bifunctional Pd-Cu / molecular sieve catalyst. Pd serves as the main component of the oxidation active center, and Cu modulates the oxidation function of Pd with the aim of improving the esterification selectivity. It was found that the selection of molecular sieves with stronger acid centers has an obvious influence on the activity and esterification selectivity. At a reaction temperature of 150 °C, the conversion rate of ethanol is 84.5%, and the selectivity of ethyl acetate is 71.2%. The selectivity of ethyl acetate of this catalyst is too low.

[0006] Ding Jian et al. (Journal of Sol-Gel Science and Technology, Vol. 2, No. 85, 2018, pp. 382 - 393) used CuO-ZnO-Al 2 O 3 -ZrO 2 as a catalyst. At a reaction temperature of 230 °C, the conversion rate of ethanol is 62.2%, the selectivity of ethyl acetate is 92.5%, and it has a stability of more than 600 hours. The activity of this catalyst is relatively low, the selectivity of ethyl acetate is relatively low, and the selectivity of the key by-product methyl ethyl ketone is not described.

[0007] E. Santacesaria et al. (The Chemical Engineering Journal, Vol. 1, No. 179, 2012, pp. 209 - 220) prepared a Cu / Cr 2 O 3 catalyst, which showed good catalytic performance. At a reaction temperature of 220 - 240 °C, a reaction pressure of 2 MPa, and a raw material ethanol flow rate of 98 g(hmol) -1 , the conversion rate of ethanol is 65%, the selectivity of ethyl acetate is 98 - 99%, and it has good stability. However, in this method, chromium is a heavy metal element that pollutes the environment and affects the health of organisms and humans, and it is not suitable for industrialization.

[0008] Currently, in the method of preparing ethyl acetate by dehydrogenation of ethanol, CuO / ZnO / Al 2 O 3 / ZrO 2As a catalyst, although it has relatively good performance, its stability is relatively poor. In addition, there are deficiencies such as high selectivity of by-product methyl ethyl ketone and difficulty in azeotropic separation of methyl ethyl ketone and ethyl acetate. Therefore, improving the ethanol conversion rate and reducing the selectivity of methyl ethyl ketone are a hot research direction in the dehydrogenation of ethanol to ethyl acetate. SUMMARY OF THE INVENTION

[0009] In view of the above-mentioned prior art situation, the present inventors have conducted extensive and in-depth research on the catalyst for dehydrogenation of ethanol to ethyl acetate, with a view to finding a catalyst for dehydrogenation of ethanol to ethyl acetate that can overcome the above-mentioned disadvantages existing in the prior art.

[0010] The present inventors have found that in the preparation process of the CuO / ZnO / Al 2 O 3 / ZrO 2 catalyst, by adding an alcohol solvent and silica, a CuO / ZnO / Al 2 O 3 / ZrO 2 / SiO 2 catalyst with a high specific surface area can be obtained. This catalyst has a large specific surface area and a high Cu specific surface area. Due to its small particle size, high specific surface area and high Cu dispersion, ethanol can be efficiently converted into ethyl acetate. The conversion rate of ethanol can be as high as 71.05%, the selectivity of ethyl acetate can be as high as 94.55%, and the selectivity of methyl ethyl ketone can be as low as 1.32%. In addition, this catalyst has good stability, and the stable reaction time after the induction period of the catalyst can exceed 1000 hours.

[0011] An object of the present invention is to provide a CuO / ZnO / Al 2 O 3 / ZrO 2 / SiO 2 catalyst, which has small particle size, high specific surface area and high Cu dispersion, and maintains a high ethanol conversion rate when used in the dehydrogenation of ethanol to ethyl acetate. In addition, this catalyst has a nano-scale particle size and has good stability.

[0012] Another object of the present invention is to provide a method for preparing the catalyst of the present invention.

[0013] Another object of the present invention is to provide the use of the catalyst of the present invention in the dehydrogenation of ethanol to ethyl acetate.

[0014] The technical solutions for achieving the above objects of the present invention can be generally summarized as follows:

[0015] 1. A CuO / ZnO / Al 2 O 3 / ZrO 2 / SiO 2 Catalyst

[0016] 2. The catalyst according to item 1, which has a specific surface area of 70 - 1000 m 2 / g, preferably 90 - 700 m 2 / g, more preferably 110 - 500 m 2 / g, most preferably 120 - 200 m 2 / g, a Cu specific surface area of 15 - 100 m 2 / g, preferably 20 - 60 m 2 / g, more preferably 20 - 50 m 2 / g, most preferably 20 - 30 m 2 / g, and an average particle size of 2 - 100 nm, preferably 2 - 80 nm, more preferably 3 - 60 nm.

[0017] 3. The catalyst according to item 1 or 2, wherein the content of CuO is 5 - 80 mol%, preferably 10 - 70 mol%, more preferably 20 - 60 mol%; the content of ZnO is 0.5 - 20 mol%, preferably 1 - 15 mol%, more preferably 2 - 10 mol%; the content of Al 2 O 3 is 1 - 50 mol%, preferably 5 - 40 mol%, more preferably 10 - 30 mol%; the content of ZrO 2 is 0.5 - 20 mol%, preferably 1 - 15 mol%, more preferably 2 - 10 mol%; the content of silica is 1 - 60 mol%, preferably 5 - 40 mol%, more preferably 6 - 25 mol%; in each case based on the total amount of the catalyst.

[0018] 4. A method for preparing the catalyst according to any one of items 1 - 3, which comprises the following steps:

[0019] (1) Adding copper salt, zinc salt, aluminum salt and zirconium salt to a mixture of water and alcohol;

[0020] (2) Adding the mixture obtained in step (1) and an alkali dropwise to an aqueous mixture of alcohol and a silicon source to obtain a viscous substance;

[0021] (3) Calcining the viscous substance obtained in step (2).

[0022] 5. The method according to item 4, wherein the copper salt is a soluble copper salt, preferably copper sulfate, copper chloride or copper nitrate; the zinc salt is a soluble zinc salt, preferably zinc sulfate, zinc chloride, zinc nitrate or zinc dihydrogen phosphate; the aluminum salt is a soluble aluminum salt, preferably aluminum chloride, aluminum sulfate or aluminum nitrate; the zirconium salt is a soluble zirconium salt, preferably zirconium chloride, zirconium sulfate or zirconium nitrate.

[0023] 6. The method according to item 4 or 5, wherein in step (2), the pH value of the reaction system is maintained at 7.5 - 12, preferably 8 - 11, more preferably 8.5 - 10.

[0024] 7. The method according to any one of items 4 - 6, wherein step (2) is carried out under heating and stirring.

[0025] 8. The method according to item 7, wherein the heating temperature is 30 - 120 °C, preferably 40 - 100 °C, more preferably 50 - 90 °C.

[0026] 9. The method according to any one of items 4 - 8, wherein the alcohols in steps (1) and (2) are independently alkanols, preferably C 1 -C 8 alkanols, more preferably one or more of methanol, ethanol, n - propanol or isopropanol.

[0027] 10. The method according to any one of items 4 - 9, wherein in steps (1) and (2), the weight ratio of water to alcohol is 1:10 to 10:1, preferably 1:5 to 5:1.

[0028] 11. The method according to any one of items 4 - 10, wherein in step (2), the silicon source is selected from one or more of water glass, solid silica gel, silica sol or fumed silica, preferably selected from silica sol or fumed silica.

[0029] 12. A catalyst obtained by the method according to any one of items 4 - 11.

[0030] 13. Use of the catalyst according to any one of items 1 - 3 or 12 in the dehydrogenation of ethanol to ethyl acetate. Detailed Description of the Invention

[0031] The present invention will be described in more detail below.

[0032] According to the first aspect of the present invention, a CuO / ZnO / Al 2 O 3 / ZrO 2 / SiO 2 catalyst is provided.

[0033] The catalyst has a specific surface area of 70 - 1000 m 2 / g, preferably 90 - 700 m 2 / g, more preferably 110 - 500 m 2 / g, most preferably 120 - 200 m 2 / g, and a pore volume of 15 - 100 m 2 / g, preferably 20 - 60 m 2 / g, more preferably 20 - 50 m 2 / g, most preferably 20 - 30 m 2 a Cu specific surface area of from 2 - 100 nm, preferably 2 - 80 nm, more preferably 3 - 60 nm in average particle size.

[0034] In one embodiment of the present invention, the catalyst has a small particle size, a large specific surface area and a high Cu specific surface area. It has surprisingly been found that these properties can greatly improve the conversion of the reactants and the selectivity of the products.

[0035] In one embodiment of the present invention, the content of CuO is 5 - 80 mol%, preferably 10 - 70 mol%, more preferably 20 - 60 mol%; the content of ZnO is 0.5 - 20 mol%, preferably 1 - 15 mol%, more preferably 2 - 10 mol%; Al 2 O 3 has a content of 1 - 50 mol%, preferably 5 - 40 mol%, more preferably 10 - 30 mol%; ZrO 2 has a content of 0.5 - 20 mol%, preferably 1 - 15 mol%, more preferably 2 - 10 mol%; the content of silica is 1 - 60 mol%, preferably 5 - 40 mol%, more preferably 6 - 25 mol%; in each case based on the total amount of the catalyst.

[0036] According to a second aspect of the present invention, there is provided a method for preparing the catalyst of the present invention, which comprises the following steps:

[0037] (1) adding a copper salt, a zinc salt, an aluminum salt and a zirconium salt to a mixture of water and alcohol;

[0038] (2) dropping the mixture obtained in step (1) and an alkali into an aqueous mixture of alcohol and a silicon source to obtain a viscous substance;

[0039] (3) calcining the viscous substance obtained in step (2).

[0040] According to the method of the present invention, in step (1), the copper salt is a soluble copper salt, preferably copper sulfate, copper chloride or copper nitrate; the zinc salt is a soluble zinc salt, preferably zinc sulfate, zinc chloride, zinc nitrate or zinc dihydrogen phosphate; the aluminum salt is a soluble aluminum salt, preferably aluminum chloride, aluminum sulfate or aluminum nitrate; the zirconium salt is a soluble zirconium salt, preferably zirconium chloride, zirconium sulfate or zirconium nitrate.

[0041] In step (1), the copper salt, zinc salt, aluminum salt, and zirconium salt are added to a mixture of water (preferably deionized water) and alcohol in a conventional manner. For example, each salt can be added to the mixed solution of water and alcohol at 5 - 55 °C (preferably room temperature (25 °C)) under stirring conditions to form a homogeneous mixture. The weight ratio of water to salt can be 3 - 30, and the preferred ratio is 6 - 20. The weight ratio of water to alcohol can be 1:10 to 10:1, preferably 1:5 to 5:1. The dosage of each of the copper salt, zinc salt, aluminum salt, and zirconium salt should ensure the above content of the corresponding metal oxide in the final catalyst.

[0042] According to the method of the present invention, in step (2), the mixture obtained in step (1) and the base are added dropwise to an aqueous mixture of alcohol and a silicon source. The dropping time can be 30 minutes to 8 hours, preferably 1 - 5 hours. There is no particular limitation on the dropping order of the mixture obtained in step (1) and the base. For example, the mixture obtained in step (1) can be added dropwise first, and then the base can be added after the dropping of the mixture is completed; or the base can be added dropwise first, and then the mixture obtained in step (1) can be added; or one of them can be added dropwise first, and after a certain period of time from the start of the dropping, the other one can be added; or both can be added dropwise simultaneously and end simultaneously. Preferably, the mixture obtained in step (1) and the base are added dropwise simultaneously and end simultaneously.

[0043] According to the method of the present invention, in step (2), the base is a water-soluble inorganic base, such as an alkali metal hydroxide or an alkali metal carbonate, preferably sodium hydroxide or sodium carbonate.

[0044] Step (2) is carried out under heating and stirring. The heating temperature can be 30 - 120 °C, preferably 40 - 100 °C, more preferably 50 - 90 °C; the stirring speed can be 200 - 600 rpm.

[0045] According to the method of the present invention, in step (2), the pH value of the reaction system is maintained at 7.5 - 12, preferably 8 - 11, more preferably 8.5 - 10. In step (2), the base is used in an amount to reach the above pH value.

[0046] According to the method of the present invention, the alcohols in steps (1) and (2) are independently alkanols, preferably C 1 -C 8 alkanols, more preferably one or more of methanol, ethanol, n-propanol, or isopropanol. The weight ratio of water to alcohol can be 1:10 to 10:1, preferably 1:5 to 5:1.

[0047] According to the method of the present invention, in step (2), the silicon source is selected from one or more of water glass, solid silica gel, silica sol, or fumed silica, preferably selected from silica sol or fumed silica. The dosage of the silicon source should ensure the above content of silica in the final catalyst.

[0048] After the dropping is completed, the mixture can be continuously stirred within the above temperature range, for example, stirred for 5 minutes to 5 hours, preferably 10 minutes to 1 hour, more preferably 10 - 50 minutes.

[0049] According to the method of the present invention, in step (3), the viscous substance obtained in step (2) is calcined. The calcination temperature can be 150 - 800 °C, and the calcination time can be 1 - 12 hours. Preferably, the calcination temperature is 200 - 700 °C, and the calcination time is 1 - 12 hours. More preferably, the calcination temperature is 200 - 600 °C, and the calcination time is 2 - 10 hours. Further preferably, the calcination temperature is 250 - 500 °C, and the calcination time is 2 - 6 hours.

[0050] According to the method of the present invention, in step (3), before calcination, the viscous substance obtained in step (2) can be allowed to stand, filtered, washed, and dried. The standing time can be 30 minutes to 10 hours, preferably 1 - 5 hours. After standing, the obtained viscous substance can be filtered, washed, and dried. There are no particular limitations on the washing, and usually, it is washed with water one or more times until the washing liquid is neutral. There are no particular limitations on the drying conditions. Preferably, the drying conditions include: the drying temperature is 50 - 160 °C; the drying time is 3 - 48 hours. Further preferably, the drying temperature is 60 - 150 °C; the drying time is 6 - 24 hours. Particularly preferably, the drying temperature is 60 - 100 °C; the drying time is 6 - 20 hours. There are no particular limitations on the drying method. For example, ordinary heating drying, microwave drying, and / or spray drying can be used, and spray drying is preferred.

[0051] After calcination, steps such as shaping, crushing, and screening can be optionally carried out.

[0052] Shaping can be carried out according to conventional methods. The shaping method can be, for example, tableting, rolling ball shaping, or extrusion shaping. At this time, a binder can be optionally added to facilitate processing and shaping. After shaping, the shaped material can be optionally crushed and then screened.

[0053] According to the third aspect of the present invention, there is provided the use of the catalyst of the present invention or the catalyst obtained by the method of the present invention in the dehydrogenation of ethanol to ethyl acetate.

[0054] In the dehydrogenation of ethanol to ethyl acetate, ethanol is passed through a catalyst bed under dehydrogenation conditions. The ethanol used can be ethanol vapor or ethanol liquid. The ethanol can be anhydrous ethanol or 95% ethanol.

[0055] When using ethanol vapor for the reaction, the ethanol is evaporated, preferably into a carrier gas. The carrier gas can be any gas that is inert to the reaction, such as an inert gas or nitrogen, preferably nitrogen. At this time, the dehydrogenation conditions can include: the temperature of the ethanol vapor is 100 - 300 °C, preferably 150 - 250 °C. The gas hourly space velocity of the ethanol vapor is 0.2 - 3 g / g 催化剂 ·h -1 , preferably 1 - 2.5 g / g 催化剂 ·h -1 . The reaction pressure is 0.1 - 5.0 MPa, preferably 1.5 - 4.5 MPa.

[0056] When using liquid ethanol, the dehydrogenation conditions can include: the reaction temperature is 80 - 300 °C, preferably 150 - 250 °C; the reaction pressure is 0.1 - 5.0 MPa, preferably 0.5 - 2.0 MPa; the liquid hourly space velocity of ethanol is 0.1 - 10 g / ml·h -1 , preferably 0.2 - 5 g / ml·h -1 .

[0057] Before being used for the catalytic dehydrogenation of ethanol to ethyl acetate, the catalyst needs to be activated, that is, reduced. The reduction conditions are conventional. Generally speaking, the reducing gas uses hydrogen or a mixture gas containing hydrogen and a gas that is inert to this reduction reaction, preferably a mixture of H 2 and N 2 mixed gas, such as a mixed gas of 15 vol% H 2 and 85 vol% N 2 . The reduction temperature is usually 100 - 300 °C, preferably 150 - 250 °C. The reduction time is usually 2 - 48 hours, preferably 3 - 24 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 shows the microscopic morphology of the catalyst obtained in Example 1 of the present invention;

[0059] Figure 2 shows the microscopic morphology of the catalyst obtained in Example 2 of the present invention;

[0060] Figure 3 shows the microscopic morphology of the catalyst obtained in Example 3 of the present invention;

[0061] Figure 4 shows the microscopic morphology of the catalyst obtained in Example 4 of the present invention;

[0062] Figure 5 shows the microscopic morphology of the catalyst obtained in Example 5 of the present invention;

[0063] Figure 6 shows the microscopic morphology of the catalyst obtained in Example 6 of the present invention;

[0064] Figure 7 shows the microscopic morphology of the catalyst obtained in Example 7 of the present invention;

[0065] Figure 8 shows the microscopic morphology of the catalyst obtained in Example 8 of the present invention;

[0066] Figure 9 shows the microscopic morphology of the catalyst obtained in Example 9 of the present invention;

[0067] Figure 10 shows the microscopic morphology of the catalyst obtained in Example 10 of the present invention;

[0068] Figure 11 shows the microscopic morphology of the catalyst obtained in Example 11 of the present invention.

[0069] Example

[0070] The present invention is described in detail below with reference to examples and comparative examples, but the scope of the present invention is not limited to these examples.

[0071] In the following examples and comparative examples, gas chromatography was used to analyze each component in the system, and quantitative analysis was carried out by the corrected normalization method.

[0072] The specific surface area of the catalyst was measured by N 2 Physical adsorption was measured using a Micromeritics ASAP 2020 at -196 °C (liquid nitrogen temperature). First, the catalyst sample was evacuated to 70 mmHg at 300 °C and heat-treated under this condition for 3 hours to remove trace water and impurities adsorbed on the catalyst surface. Then, the adsorption-desorption isotherm was measured by the static method. The specific surface area of the catalyst was calculated by the BET (Bnmauer-Emmet-Teller) theory in combination with the adsorption isotherm.

[0073] The Cu specific surface area of the catalyst was measured by H 2 -TPR test, which was carried out on a BELCAT-BCAT-302 device of a chemisorption instrument of Japan BEL Company. 0.1 g of the sample was placed in a U-tube of the chemisorption instrument, and after purging with He gas at 300 °C for 20 minutes, the temperature-raising reduction test preparation was carried out. Reduction was carried out with H 2 gas. Before each test, the sample was dehydrated in a He atmosphere at 300 °C for 35 minutes. The Cu specific surface area was measured by the pulse method by introducing N 2 O gas into the sample until saturation, and the total gas consumption was used for measurement.

[0074] The average particle size of the catalyst was measured by XRD using a German desktop X-ray diffractometer BRUKER-D2 PHASER 2ndGen. The measurement conditions were with a power of 3 kW, a tube voltage of 30 kV, a tube current of 20 mA, and a scanning speed of 0.03° / s. It was calculated by the Scherrer formula D = Kλ / Bcosθ.

[0075] The microscopic physical morphology of the catalyst was observed using a transmission electron microscope model JSM-IT700HR / LA produced by JEOL, Japan, with an acceleration voltage set at 3.0 kV. The content of each component of the catalyst was determined by ICP-MS model 7900 produced by Agilent using the I.C.P method.

[0076] Example 1

[0077] 1. Preparation of the catalyst:

[0078] (1) Weigh 19.5 g of copper nitrate (Kanto Chemical Co., Japan), 2.0 g of zinc nitrate (Kanto Chemical Co., Japan), 10.1 g of aluminum nitrate (Kanto Chemical Co., Japan), and 3.6 g of zirconium nitrate (Kanto Chemical Co., Japan), and dissolve them in a mixed solution of 250 g of deionized water and 250 g of ethanol.

[0079] (2) Weigh 17.9 g of sodium hydroxide (Kanto Chemical Co., Japan) and dissolve it in 100 g of deionized water.

[0080] (3) Drop the homogeneous mixture obtained in step (1) and the sodium hydroxide solution obtained in step (2) simultaneously into a mixture of 250 g of water, 250 g of ethanol, and 1.27 g of fumed silica (Aerosil 380 of Nippon Aerosil), and stir at 70 °C and a stirring speed of 300 rpm, maintaining the pH value of the mixed solution at 9.0, with a dropping time of 2 hours.

[0081] (4) After the dropping is completed, stir the viscous substance obtained in step (3) at 70 °C and 300 rpm for 30 minutes, and then let it stand for 4 hours. Filter the standing viscous substance, wash it with deionized water until the washing liquid is neutral. Then dry it at 80 °C for 12 hours and calcine it at 400 °C for 3 hours to obtain 32 g of composite catalyst powder. Press the obtained composite catalyst powder into tablets, crush and screen it to obtain granular catalyst with a particle size of 20 - 40 mesh, namely the composite catalyst CuO / ZnO / Al 2 O 3 / ZrO 2 / SiO 2 .

[0082] The specific surface area of the obtained catalyst particles was measured to be 163.17 m 2 / g, the specific surface area of Cu was 29.55 m 2 / g, and the average particle size was 10 nm. The content of copper in the catalyst in terms of CuO was 54.20 mol%. The content of zinc in the catalyst in terms of ZnO was 4.52 mol%. The content of aluminum in the catalyst in terms of Al 2 O 3 was 18.07 mol%. The content of zirconium in the catalyst in terms of ZrO 2 was 9.03 mol%. The content of silica in the catalyst was 14.18 mol%.

[0083] 2. Performance evaluation of the catalyst

[0084] 2 g of the catalyst particles prepared above were placed into a vertical tubular fixed-bed reactor with an inner diameter of 10 mm and a height of 40 cm. Before the reaction evaluation, the catalyst was reduced under the following conditions: a mixed gas of 15 vol% H 2 and 85 vol% N 2 flowed through the catalyst bed from the top of the reactor at a flow rate of 120 ml / min and was discharged from the bottom of the reactor. The reduction temperature was 200 °C and the reduction time was 12 hours. After the reduction was completed, the reduction gas was replaced with pure nitrogen, the pressure of the reaction system was increased to 0.9 MPa, and the temperature of the catalyst bed was increased to 220 °C. Then, 99.5 wt% ethanol liquid was introduced and entered the tubular reactor from the top. After the reaction, the product was discharged from the bottom of the reactor. The reaction conditions were as follows: the liquid hourly space velocity of ethanol was 0.5 g / ml·h, the reaction temperature was 220 °C, and the reaction pressure was 0.9 MPa. After 4 hours of reaction, samples were taken for analysis to determine the conversion rate of ethanol and the product distribution.

[0085] The conversion rate of ethanol was 71.05%, the selectivity to ethyl acetate was 94.55%, and the selectivity to the by-product methyl ethyl ketone was 1.32%. The stable reaction time after the catalyst induction period exceeded 1000 hours.

[0086] Example 2

[0087] Preparation of the catalyst:

[0088] It was basically the same as in Example 1, except that ethanol in steps (1) and (3) was changed to methanol, and the feed amount was changed from 250 g to 220 g.

[0089] The specific surface area of the obtained catalyst was measured to be 160.07 m 2 / g, the specific surface area of Cu was 26.14 m 2 / g, the average particle size is 15 nm. The content of copper in the catalyst calculated as CuO is 54.09 mol%. The content of zinc in the catalyst calculated as ZnO is 4.57 mol%. The content of aluminum in the catalyst calculated as Al 2 O 3 is 18.10 mol%. The content of zirconium in the catalyst calculated as ZrO 2 is 9.00 mol%. The content of silica in the catalyst is 14.24 mol%.

[0090] Performance evaluation of the catalyst: The conversion rate of ethanol is 70.85%, the selectivity of ethyl acetate is 94.02%, and the selectivity of the by-product methyl ethyl ketone is 1.36%. After the induction period of the catalyst, the stable reaction time reaches 800 hours.

[0091] Example 3

[0092] Preparation of the catalyst:

[0093] It is basically the same as Example 1, except that ethanol in steps (1) and (3) is changed to n-propanol, and the feed amount is changed from 250 g to 220 g.

[0094] It is measured that the specific surface area of the obtained catalyst is 148.60 m 2 / g, the Cu specific surface area is 25.84 m 2 / g, the average particle size is 50 nm. The content of copper in the catalyst calculated as CuO is 53.20 mol%. The content of zinc in the catalyst calculated as ZnO is 4.02 mol%. The content of aluminum in the catalyst calculated as Al 2 O 3 is 18.57 mol%. The content of zirconium in the catalyst calculated as ZrO 2 is 9.53 mol%. The content of silica in the catalyst is 14.68 mol%.

[0095] Performance evaluation of the catalyst: The conversion rate of ethanol is 70.47%, the selectivity of ethyl acetate is 92.55%, and the selectivity of the by-product methyl ethyl ketone is 1.94%. After the induction period of the catalyst, the stable reaction time reaches 720 hours.

[0096] Example 4

[0097] Preparation of the catalyst:

[0098] It is basically the same as Example 1, except that ethanol in steps (1) and (3) is changed to isopropanol, and the feed amount is changed from 250 g to 240 g.

[0099] It is measured that the specific surface area of the obtained catalyst is 145.18 m 2 / g, the Cu specific surface area is 24.69 m2 / g, with an average particle size of 52 nm. The content of copper in the catalyst in terms of CuO is 54.11 mol%. The content of zinc in the catalyst in terms of ZnO is 4.32 mol%. Aluminum in terms of Al 2 O 3 in the catalyst is 18.16 mol%. The content of zirconium in the catalyst in terms of ZrO 2 is 9.13 mol%. The content of silica in the catalyst is 14.28 mol%.

[0100] Performance evaluation of the catalyst: The conversion rate of ethanol is 71.05%, the selectivity for ethyl acetate is 91.38%, and the selectivity for the by-product methyl ethyl ketone is 2.06%. After the induction period of the catalyst, the stable reaction time reaches 700 hours.

[0101] Example 5

[0102] Preparation of the catalyst:

[0103] Basically the same as Example 1, except that the fumed silica added in step (3) is changed to 40 wt% silica sol (Sigma-Aldrich, HS-40 colloidal silica, a 40 wt% suspension in water), and the feed amount is changed from 1.27 g to 3.18 g.

[0104] It was measured that the specific surface area of the obtained catalyst is 158.32 m 2 / g, the Cu specific surface area is 28.64 m 2 / g, and the average particle size is 10 nm. The content of copper in the catalyst in terms of CuO is 54.36 mol%. The content of zinc in the catalyst in terms of ZnO is 4.25 mol%. Aluminum in terms of Al 2 O 3 in the catalyst is 18.02 mol%. The content of zirconium in the catalyst in terms of ZrO 2 is 9.10 mol%. The content of silica in the catalyst is 14.27 mol%.

[0105] Performance evaluation of the catalyst: The conversion rate of ethanol is 69.94%, the selectivity for ethyl acetate is 93.86%, and the selectivity for the by-product methyl ethyl ketone is 1.59%. After the induction period of the catalyst, the stable reaction time reaches 652 hours.

[0106] Example 6

[0107] Preparation of the catalyst:

[0108] Basically the same as Example 1, except that the fumed silica added in step (3) was changed to 38 wt% of sodium silicate solution (about 38% sodium silicate solution, Fujifilm Wako Pure Chemical Corporation), and the feeding amount was changed from 1.27 g to 3.34 g.

[0109] It was measured that the specific surface area of the obtained catalyst was 135.24 m 2 / g, the Cu specific surface area was 24.53 m 2 / g, and the average particle size was 11 nm. The content of copper in the catalyst in terms of CuO was 54.37 mol%. The content of zinc in the catalyst in terms of ZnO was 4.45 mol%. Aluminum was in the form of Al 2 O 3 and its content in the catalyst was 18.05 mol%. Zirconium was in the form of ZrO 2 and its content in the catalyst was 8.88 mol%. The content of silica in the catalyst was 14.25 mol%.

[0110] Performance evaluation of the catalyst: The conversion rate of ethanol was 65.28%, the selectivity to ethyl acetate was 90.14%, and the selectivity to the by-product methyl ethyl ketone was 3.05%. After the induction period of the catalyst, the stable reaction time reached 932 hours.

[0111] Example 7

[0112] Preparation of the catalyst:

[0113] Basically the same as Example 1, except that the fumed silica added in step (3) was changed to 93 wt% of solid silica gel (model: TN-7X0, Guangdong Chaote New Materials Technology Co., Ltd.), and the feeding amount was changed from 1.27 g to 1.37 g.

[0114] It was measured that the specific surface area of the obtained catalyst was 124.48 m 2 / g, the Cu specific surface area was 19.93 m 2 / g, and the average particle size was 12 nm. The content of copper in the catalyst in terms of CuO was 54.22 mol%. The content of zinc in the catalyst in terms of ZnO was 4.48 mol%. Aluminum was in the form of Al 2 O 3 and its content in the catalyst was 18.09 mol%. Zirconium was in the form of ZrO 2 and its content in the catalyst was 9.04 mol%. The content of silica in the catalyst was 14.17 mol%.

[0115] Performance evaluation of the catalyst: The conversion rate of ethanol was 64.82%, the selectivity for ethyl acetate was 89.54%, and the selectivity for the by-product methyl ethyl ketone was 3.72%. After the induction period of the catalyst, the stable reaction time reached 900 hours.

[0116] Example 8

[0117] Preparation of the catalyst:

[0118] Basically the same as Example 1, except that the feed amount of fumed silica in step (3) was changed from 1.27 g to 0.60 g.

[0119] It was determined that the specific surface area of the obtained catalyst was 125.82 m 2 / g, the Cu surface area was 21.94 m 2 / g, and the average particle size was 53 nm. The content of copper in the catalyst in terms of CuO was 58.57 mol%. The content of zinc in the catalyst in terms of ZnO was 4.88 mol%. The content of aluminum in the catalyst in terms of Al 2 O 3 was 19.52 mol%. The content of zirconium in the catalyst in terms of ZrO 2 was 9.76 mol%. The content of silica in the catalyst was 7.27 mol%.

[0120] Performance evaluation of the catalyst: The conversion rate of ethanol was 68.45%, the selectivity for ethyl acetate was 91.83%, and the selectivity for the by-product methyl ethyl ketone was 1.98%. After the induction period of the catalyst, the stable reaction time reached 700 hours.

[0121] Example 9

[0122] Preparation of the catalyst:

[0123] Basically the same as Example 1, except that the feed amount of fumed silica in step (3) was changed from 1.27 g to 2.01 g.

[0124] It was determined that the specific surface area of the obtained catalyst was 134.46 m 2 / g, the Cu surface area was 22.31 m 2 / g, and the average particle size was 48 nm. The content of copper in the catalyst in terms of CuO was 50.02 mol%. The content of zinc in the catalyst in terms of ZnO was 4.17 mol%. The content of aluminum in the catalyst in terms of Al 2 O 3 was 16.67 mol%. The content of zirconium in the catalyst in terms of ZrO 2 was 8.34 mol%. The content of silica in the catalyst was 20.80 mol%.

[0125] Performance evaluation of the catalyst: The conversion rate of ethanol was 70.02%, the selectivity of ethyl acetate was 92.78%, and the selectivity of the by-product methyl ethyl ketone was 1.73%. After the induction period of the catalyst, the stable reaction time reached 700 hours.

[0126] Example 10

[0127] Preparation of the catalyst:

[0128] It was basically the same as Example 1, except that the feeding amount of fumed silica in step (3) was changed from 1.27 g to 2.85 g.

[0129] It was measured that the specific surface area of the obtained catalyst was 165.42 m 2 / g, the Cu specific surface area was 29.98 m 2 / g, and the average particle size was 53 nm. The content of copper in the catalyst calculated as CuO was 46.03 mol%. The content of zinc in the catalyst calculated as ZnO was 3.84 mol%. The content of aluminum in the catalyst calculated as Al 2 O 3 was 15.34 mol%. The content of zirconium in the catalyst calculated as ZrO 2 was 7.67 mol%. The content of silica in the catalyst was 27.12 mol%.

[0130] Performance evaluation of the catalyst: The conversion rate of ethanol was 67.17%, the selectivity of ethyl acetate was 91.19%, and the selectivity of the by-product methyl ethyl ketone was 1.94%. After the induction period of the catalyst, the stable reaction time reached 700 hours.

[0131] Example 11

[0132] Preparation of the catalyst:

[0133] It was basically the same as Example 1, except that the feeding amount of fumed silica in step (3) was changed from 1.27 g to 4.89 g.

[0134] It was measured that the specific surface area of the obtained catalyst was 167.11 m 2 / g, the Cu specific surface area was 29.89 m 2 / g, and the average particle size was 50 nm. The content of copper in the catalyst calculated as CuO was 38.57 mol%. The content of zinc in the catalyst calculated as ZnO was 3.21 mol%. The content of aluminum in the catalyst calculated as Al 2 O 3 was 12.86 mol%. The content of zirconium in the catalyst calculated as ZrO 2 was 6.43 mol%. The content of silica in the catalyst was 38.93 mol%.

[0135] Performance evaluation of the catalyst: The conversion rate of ethanol was 67.62%, the selectivity of ethyl acetate was 91.08%, and the selectivity of the by-product methyl ethyl ketone was 1.92%. After the induction period of the catalyst, the stable reaction time reached 700 hours.

[0136] Comparative Example 1

[0137] Preparation of the catalyst:

[0138] Basically the same as Example 1, except that 250 g of ethanol in steps (1) and (3) was changed to 0 g.

[0139] It was measured that the specific surface area of the obtained catalyst was 88.73 m 2 / g, the Cu specific surface area was 12.61 m 2 / g, and the average particle size was 150 nm. The content of copper in the catalyst in terms of CuO was 53.12 mol%. The content of zinc in the catalyst in terms of ZnO was 4.72 mol%. Aluminum in terms of Al 2 O 3 in the catalyst was 18.37 mol%. The content of zirconium in the catalyst in terms of ZrO 2 was 9.08 mol%. The content of silica in the catalyst was 14.71 mol%.

[0140] Performance evaluation of the catalyst: The conversion rate of ethanol was 57.15%, the selectivity of ethyl acetate was 88.52%, and the selectivity of the by-product methyl ethyl ketone was 3.93%. After the induction period of the catalyst, the stable reaction time was 12 hours and the catalyst was deactivated.

[0141] Comparative Example 2

[0142] Preparation of the catalyst:

[0143] Basically the same as Example 1, except that 250 g of ethanol in step (1) was changed to 0 g, and at the same time, all the gas-phase silica in step (3) was changed to 0 g.

[0144] It was measured that the specific surface area of the obtained catalyst was 64.08 m 2 / g, the Cu specific surface area was 14.23 m 2 / g, and the average particle size was 140 nm. The content of copper in the catalyst in terms of CuO was 63.16 mol%. The content of zinc in the catalyst in terms of ZnO was 5.26 mol%. Aluminum in terms of Al 2 O 3 in the catalyst was 21.05 mol%. The content of zirconium in the catalyst in terms of ZrO 2 was 10.53 mol%. The content of silica in the catalyst was 0 mol%.

[0145] Performance evaluation of the catalyst: The conversion rate of ethanol was 56.74%, the selectivity of ethyl acetate was 86.93%, and the selectivity of the by-product methyl ethyl ketone was 3.96%. After the induction period of the catalyst, the stable reaction time was 14 hours, and then the catalyst deactivated.

[0146] Comparative Example 3

[0147] Preparation of the catalyst:

[0148] Basically the same as in Example 1, except that 250 g of ethanol in Steps (1) and (3) was changed to 0 g, and at the same time, 0 g of fumed silica in Step (3) was used.

[0149] It was measured that the specific surface area of the obtained catalyst was 59.28 m 2 / g, the Cu specific surface area was 14.79 m 2 / g, and the average particle size was 160 nm. The content of copper in the catalyst in terms of CuO was 63.14 mol%. The content of zinc in the catalyst in terms of ZnO was 5.06 mol%. The content of aluminum in the catalyst in terms of Al 2 O 3 was 21.14 mol%. The content of zirconium in the catalyst in terms of ZrO 2 was 10.66 mol%. The content of silica in the catalyst was 0 mol%.

[0150] Performance evaluation of the catalyst: The conversion rate of ethanol was 54.87%, the selectivity of ethyl acetate was 82.53%, and the selectivity of the by-product methyl ethyl ketone was 4.07%. After the induction period of the catalyst, the stable reaction time was 10 hours, and then the catalyst deactivated.

[0151] Comparative Example 4

[0152] Preparation of the catalyst:

[0153] Basically the same as in Example 1, except that the fumed silica in Step (3) was changed to 0 g.

[0154] It was measured that the specific surface area of the obtained catalyst was 52.39 m 2 / g, the Cu specific surface area was 13.80 m 2 / g, and the average particle size was 162 nm. The content of copper in the catalyst in terms of CuO was 63.06 mol%. The content of zinc in the catalyst in terms of ZnO was 5.46 mol%. The content of aluminum in the catalyst in terms of Al 2 O 3 was 21.01 mol%. The content of zirconium in the catalyst in terms of ZrO 2 was 10.47 mol%. The content of silica in the catalyst was 0 mol%.

[0155] Performance evaluation of the catalyst: The conversion rate of ethanol was 52.98%, the selectivity of ethyl acetate was 83.64%, and the selectivity of the by-product methyl ethyl ketone was 5.18%. After 15 hours of stable reaction time after the catalyst induction period, the catalyst became deactivated.

[0156] Comparative Example 5

[0157] Preparation of the catalyst:

[0158] Basically the same as Example 1, except that the pH value of the mixed solution in step (3) was changed from 9.0 to 5.0, which was achieved by dropping less sodium hydroxide than in Example 1.

[0159] It was measured that the specific surface area of the obtained catalyst was 138.32 m 2 / g, the specific surface area of Cu was 24.51 m 2 / g, and the average particle size was 17 nm. The content of copper in the catalyst in terms of CuO was 54.63 mol%. The content of zinc in the catalyst in terms of ZnO was 4.19 mol%. The content of aluminum in the catalyst in terms of Al 2 O 3 was 18.47 mol%. The content of zirconium in the catalyst in terms of ZrO 2 was 8.32 mol%. The content of silica in the catalyst was 14.39 mol%.

[0160] Performance evaluation of the catalyst: The conversion rate of ethanol was 63.90%, the selectivity of ethyl acetate was 92.37%, and the selectivity of the by-product methyl ethyl ketone was 2.48%. After 18 hours of stable reaction time after the catalyst induction period, the catalyst became deactivated.

[0161] The performance of the catalysts obtained from each example is summarized in Table 1 below.

[0162] Table 1

[0163]

Claims

1. A CuO / ZnO / Al2O3 / ZrO2 / SiO2 catalyst.

2. The catalyst as claimed in claim 1, having a molecular weight of 70-1000 m 2 / g, preferably 90-700m 2 / g, more preferably 110-500m 2 / g, most preferably 120-200m 2 / g specific surface area, 15-100m 2 / g, preferably 20-60m 2 / g, more preferably 20-50m 2 / g, most preferably 20-30m 2 / g of Cu specific surface area and an average particle size of 2-100nm, preferably 2-80nm, more preferably 3-60nm.

3. A catalyst as claimed in claim 1 or 2, wherein the content of CuO is 5-80 mol %, preferably 10-70 mol %, more preferably 20-60 mol %; the content of ZnO is 0.5-20 mol %, preferably 1-15 mol %, more preferably 2-10 mol %; the content of Al2O3 is 1-50 mol %, preferably 5-40 mol %, more preferably 10-30 mol %; the content of ZrO2 is 0.5-20 mol %, preferably 1-15 mol %, more preferably 2-10 mol %; the content of silicon dioxide is 1-60 mol %, preferably 5-40 mol %, more preferably 6-25 mol %; in each case based on the total amount of catalyst.

4. A method for preparing the catalyst according to any one of claims 1 to 3, comprising the steps of: (1) adding copper salt, zinc salt, aluminum salt and zirconium salt to a mixture of water and alcohol; (2) adding the mixture obtained in step (1) and a base dropwise to an aqueous mixture of an alcohol and a silicon source to obtain a viscous substance; (3) calcining the viscous material obtained in step (2).

5. The method according to claim 4, wherein the copper salt is a soluble copper salt, preferably copper sulfate, copper chloride or copper nitrate; the zinc salt is a soluble zinc salt, preferably zinc sulfate, zinc chloride, zinc nitrate or zinc dihydrogen phosphate; the aluminum salt is a soluble aluminum salt, preferably aluminum chloride, aluminum sulfate or aluminum nitrate; the zirconium salt is a soluble zirconium salt, preferably zirconium chloride, zirconium sulfate or zirconium nitrate.

6. The method according to claim 4 or 5, wherein in step (2), the pH value of the reaction system is maintained at 7.5-12, preferably 8-11, and more preferably 8.5-10.

7. The method according to any one of claims 4 to 6, wherein step (2) is carried out under heating and stirring.

8. The method according to claim 7, wherein the heating temperature is 30-120°C, preferably 40-100°C, more preferably 50-90°C.

9. The method according to any one of claims 4 to 8, wherein the alcohol in steps (1) and (2) is independently an alkanol, preferably a C1-C8 alkanol, more preferably one or more of methanol, ethanol, n-propanol or isopropanol.

10. The method according to any one of claims 4 to 9, wherein in steps (1) and (2), the weight ratio of water to alcohol is 1:10 to 10:1, preferably 1:5 to 5:

1.

11. The method according to any one of claims 4 to 10, wherein in step (2), the silicon source is selected from one or more of water glass, solid silica gel, silica sol or fumed silica, preferably selected from silica sol or fumed silica.

12. A catalyst obtained by the process as claimed in any one of claims 4 to 11.

13. Use of the catalyst according to any one of claims 1 to 3 or 12 in the dehydrogenation of ethanol to produce ethyl acetate.

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